Status of T2K Target 2 nd Oxford-Princeton High-Power Target Workshop 6-7 th November 2008 Mike Fitton RAL.

Status of T2K Target

2nd Oxford-Princeton High-Power Target Workshop6-7th November 2008

Mike FittonRAL

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Contents of Talk

•T2K target station•Aims of target design•Current target design•CFD analysis•Remote target exchange concept•Future upgrade plans

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Inner iron shields

Inner concrete shields

Support structure= Helium vessel

Target and 1st horns2nd horns

3rd horns

Beam windowBaffle

T2K Target station area

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Baffle / Collimator

Test install into Target station October 2008

High power target group, RAL

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

4MW Hadron Absorber

T. Ishida, KEK & C. Densham, RAL

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Aims of Target Design• Target is graphite rod, 900mm long and 26mm diameter

• Target should be Helium cooled to allow higher operating temperature and to avoid shock waves from liquid coolants

• Target rod to be completely encased in titanium and cooled using high purity helium to prevent oxidation of the graphite

• The Helium should cool both upstream and downstream titanium window first, before cooling the target due to material limits

• Pressure drop in the system should be kept to a minimum due to high flow rate required (max. 0.8 bar available for target at required flow rate of 32

g/s (30% safety margin))

• Target rod to be uniformly cooled, but kept above 400°C to reduce radiation damage effects

• It should be possible to remotely change the target in the first horn

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

~940 mm

Titanium target body

Graphite(ToyoTanso IG-43)

Current Target Design

Helium cooling

Graphite to titanium diffusion bond

47.046.439.635.626.0

Ti-6Al-4V tube and windows (0.3 mm thick)

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Graphite-to-graphite bond (Nissinbo ST-201)

Flow turns 180° at downstream

window

Inlet manifold

Outlet manifold

Upstream Window

Target Design:Helium cooling path

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Target v.0 – September 2008

Target manufactured by Toshiba, JapanPipes, Isolators, remote connectors and remote handling/alignment systems by RAL

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

IG43 Graphite diffusion bonded into Ti-6Al-4V titanium, Special Techniques Group at UKAEA Culham

Diffusion Bond + Graphite-Graphite bonding test

Aluminium intermediate layer, bonding temperature 550ºCSoft aluminium layer reduces residual thermal stresses in the graphite

Graphite-Graphite bonding

Graphite transfer to Aluminium

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Testing of graphite bonding

Adhesive cured and fired to 1000°CFracture strength ~40MPaFailure through substrate, not bondline

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

CFD Analysis outline

Boundary conditions – Inlet Mass flow rate = 25g/s and 32g/s– Helium Inlet temperature = 300K – Outlet Pressure = 0.9 bar (gauge)

Heat deposition from MARS simulation– On target as a function in r and z– On upstream and downstream window as radial

function– On Inner graphite tube as a function of z– On Outer tube as a total source– TOTAL HEAT LOAD = 22kW

Required flow rate

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Velocity streamlines & Pressure drop

Maximum velocity = 476 m/s @ 32g/s Maximum velocity = 398 m/s @ 25g/s

Pressure drop = 0.545 bar @ 25g/sPressure drop = 0.792 bar @ 32g/s

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Steady state target temperature

30 GeV, 0.4735Hz, 750 kW beam

Helium mass flow rate = 32g/s

Radiation damaged graphite assumed (thermal conductivity 20 [W/m.K] at 1000K- approx 4 times lower than new graphite)

Maximum temperature = 736˚C

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Target window temperatures

Max Steady State Temperature = 92°CMax Steady State Temperature = 95°C

Upstream Window Downstream Window

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

He flow test with actual targetStatus monitor display (EPICS/EDM)

Pres

sure

Dro

p [k

Pa]

Required flow rate

Achieved mass flow is 650 [Nm3/h] … requirement + 27%(Requirement for 750kW beam = 510 [Nm3/h])

Pressure drop is consistent with theExpectation by CFD simulation byM. Fitton.

T. Nakadaira, KEK

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Target helium compressor–Power consumption: 34kW–Helium gas leak rate < 1.110-5[Pam/s]

Flow rate

Discharge pressure [MPa]

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Target installed within 1st magnetic horn

Clearance between target and horn is only 3mm

Proton beam

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Prototype Target remote exchange system

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Target remote exchange system

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Future upgrade plans

1st April 2009 – Start operation 2010 – Power to 750kW

2014 – Power to 1.66MW 20? ? – Power to 3-4MW

Only approximately 50kW deposited in target, however• With current setup helium T too high (350°C)• Need to increase flow rate Higher pressure

• May need to modify target and HX to lower P

Only Hadron absorber and DV currently designed for this power

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

IG 43 graphite200 MeV proton fluence

~10^21 p/cm2

c. 1 year operation in T2K

Water cooled

Radiation damage likely to be limiting factor for target life

Nick Simos, BNL

2nd Oxford-Princeton High-Power Target WorkshopMike Fitton

Expected radiation damage of the target– The approximation formula used by NuMI target group : 0.25dpa/year– MARS simulation: 0.15~0.20 dpa/year

Dimension change : shrinkage by ~5mm in length in 5 years at maximum. ~75μm in radius

Degradation of thermal conductivity … decreased by 97% @ 200 C 70~80% @400C

Magnitude of the damage strongly depends on the irradiation temperature. – It is better to keep the temperature of target around 400 ~ 800 C

Irradiation

Temperature(C)400 600 800 1000

2dpa

1dpa

-0.5%

Dim

ensi

on c

hang

e

1 2 3 (dpa)

400oC

800oC

Thermal conductivity (After/Before)Toyo-Tanso Co Ltd. IG-11

JAERI report (1991)

Irradiation effects on Graphite

Toyo-Tanso Co Ltd. IG-43